[pushed] Remove unnecessary call to get_thread_db_info

[Simon Marchi <simon dot marchi at ericsson dot com>]

In thread_db_detach, we call get_thread_db_info to first check if there
exists a thread_db_info entry for the pid to detach.  If there is, then
we call delete_thread_db_info.  It's unnecessary to call
get_thread_db_info in the first place, since delete_thread_db_info
handles the case where no thread_db_info entry exist for the given pid.

gdb/ChangeLog:

	* linux-thread-db.c (thread_db_detach): Remove call to
	delete_thread_db_info.
---
 gdb/ChangeLog         | 5 +++++
 gdb/linux-thread-db.c | 6 +-----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 8555b55..bba278e 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2017-12-29  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* linux-thread-db.c (thread_db_detach): Remove call to
+	delete_thread_db_info.
+
 2017-12-28  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* target.h (enum target_object) <TARGET_OBJECT_HPUX_UREGS,
diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
index 27f9ce8..7fe6e2d 100644
--- a/gdb/linux-thread-db.c
+++ b/gdb/linux-thread-db.c
@@ -1093,12 +1093,8 @@ static void
 thread_db_detach (struct target_ops *ops, const char *args, int from_tty)
 {
   struct target_ops *target_beneath = find_target_beneath (ops);
-  struct thread_db_info *info;
-
-  info = get_thread_db_info (ptid_get_pid (inferior_ptid));
 
-  if (info)
-    delete_thread_db_info (ptid_get_pid (inferior_ptid));
+  delete_thread_db_info (ptid_get_pid (inferior_ptid));
 
   target_beneath->to_detach (target_beneath, args, from_tty);
 
-- 
2.7.4